A stethoscope examination is a fundamental medical examination procedure that is part of any routine examination performed by a physician. A stethoscope examination allows the physician to analyze a patient's cardiovascular and respiratory system. To perform this analysis, the doctor uses an acoustic stethoscope to listen to the sounds generated by the patient's cardiovascular and respiratory system. The typical examination involves a doctor placing a stethoscope bell-and-diaphragm chest piece on a patient's back or chest so that the doctor is able to listen to sounds at various locations on the patient's body. The bell acts as a filter to isolate sounds in a lower frequency range, while the diaphragm filters out lower frequencies and passes higher frequency stethoscope sounds.
Although a stethoscope examination is a simple and routine procedure, it nevertheless requires that a patient be present with the doctor in an examination room. Consequently, those patients who may require frequent--perhaps even daily--stethoscope examinations are burdened by the administrative, financial, and logistical hardships involved in frequent visits to a doctor.
Patients who live a long distance from a doctor's office are particularly burdened. Patients residing in a remote location with a need to frequently see a doctor must either be admitted into a hospital (or other local facility), or be willing to hire a health care professional to visit or stay with the patient at the patient's home. For most patients, today's spiraling medical costs place both of these options out of reach.
There exists a compelling need, therefore, for a system by which a doctor can perform medical examinations on a remotely-located patient while avoiding at least some of the usual administrative, financial, and logistical hardships. Preferably, such a system would enable the doctor to perform a medical examination on a patient (such as a stethoscope examination) while the patient resides in the comfort of his or her home. Such a system would eliminate the need for the patient to travel to a doctor's office for routine stethoscope examinations. Such a system may, in some cases, also permit a patient who needs continual medical care to reside at home without hiring a health care provider to regularly visit the patient's home.
While many techniques for sensing and transmitting data from remote locations are known, acoustic stethoscope data sensed at a private home poses special problems. Fidelity of the signal presented to the doctor's ears is of utmost importance, because the doctor's diagnosis depends on subtle sound patterns. The sounds of greatest interest are relatively low frequencies (e.g., 30 to 500 Hz). But the most available data transmission channel--the ordinary home telephone line--transmits this range of frequencies very poorly.
Techniques for digitizing signals representing sounds are now well known, but the required sampling rates for good fidelity lead to bandwidth requirements that are not met by ordinary home telephone lines. And even if telephone lines could be upgraded (with attendant expense), the electronics required to digitize sound, compress the sound data, transmit the data by modem and perform the reverse at the receiving end is quite expensive. Moreover, because the loss of a single bit could result in significant distortion of the sound ultimately reconstructed, error detection/correction circuitry must be used, adding further to the costs.
Accordingly, any system used to facilitate remote stethoscopic or other medical examinations must be both cost-effective and accurate, if it is to be more efficient than a face-to-face consultation. In addition, it must provide sounds in the traditional manner, in accordance with physicians conventional stethoscope training.